Process for the manufacture of spontaneously crimping composite filaments



Jan. 10, 1967 w. G. SETTELE 3,297,307

PROCESS FOR THE MANUFACTURE OF SPONTANEOUSLY CRIMPING COMPOSITE FILAMENTS Filed June 25, 1965 2 SheetsSheet 1 zt/flfil if 2 Inventor M? rawzw Attorney 5 Jan. 10, 1967 w sETTELE 3,297,807

PROCESS FOR THE MANUFACTURE OF SPONTANEOUSLY CRIMPING GOMPOS ITE FILAMENTS Filed June 25, 1965 2 Sheets-Sheet 3 4; Fig. 6.

Inventor United States Patent PROCESS FOR THE MANUFACTURE OF SPON- TANEOUSLY CRllMPING COMPOSITE FILA- MENTS Walter G. Settele, Seeburg-Lucern, Switzerland, assignor to Societe de la Viscose Suisse, Emmenbrucke, Switzerland, a Swiss body corporate Filed June 25, 1965, Ser. No. 467,013 Claims priority, application Switzerland, Aug. 5, 1964, 10,246/64 3 Claims. (Cl. 264171) This application is a continuation-in-part of my copending application Serial No. 173,894, filed February 19, 1962, now US. Patent No. 3,192,295.

The present invention relates to the manufacture of spontaneously crimping composite filaments and includes also the crimped filaments.

The term spontaneously crimping as used in the :present specification describes the property of the filaments of crimping spontaneously immediately after having been stretched, or having been stored for some time on bobbins etc, as soon as the tension is taken off the filaments. No special treatment such as swelling, shrinking or heating is required to bring about spontaneous crimping.

Various processes for the manufacture of crimped fibres are known which impart to the fibres a heterogeneous structure and in which at the same time at least two materials are spun through a common spinneret orifice while being prevented from complete homogenisation, and the filaments are then subjected to a stretching and/ or shrinking operation. The two materials making up the monofil may lie side by side or one may form the shell and the other the core in the cross-section. The prerequisite for the success of all such processes for the manufacture of so-called composite filaments is that the two materials should not tend to separate.

There has been described the manufacture of crimpable composite yarns of polyesters and polyamides by melt spinning through one and the same spinneret orifice and then stretching the filament so formed at room temperature or at a temperature that is no higher than 70 C. below the point at which the lower-melting constituents melt. However, the composite filaments do not crimp spontaneously, and the crimp has to be developed by a shrinking treatment. Thus this type of filament like other prior art filaments is only potentially crimpable.

A feature common to all the prior art processes and the products obtained by them is that after spinning and stretching the filament is only potentially crimpable, the crimp materialising only after a shrinking treatment, such as swelling, moistening and heating the filament in the slack state.

The prior art discloses at most scanty details concerning the feature take-up Which characterises the crimp of the crimped filaments. For the purpose of the present specification, the terms take-up and number of loops have the following meanings: Take-Up, TU for short:

TU= X 100 where L is the measured length of a piece of filament in the stretched state under a tensional force just sufficient to take the crimp out without as yet drawing upon the inherent elasticity of the filament, and S is the length of the same piece of filament in the slack state.

Number of Loops is the number of loops of the crimped composite filament per cm., referred to the length L of the stretched filament.

I have found that it is possible to manufacture from certain thermoplastic organic polymers, spun from the melt side by side, useful spontaneously crimping filaments when such filaments, being composites of different polymers welded together in the longitudinal direction, are stretched while being heated.

I have invented a process for the manufacture of spontaneously crimping composite filaments made of one constituent which is a polyamide and of another constituent which is a different polyamide or a polyester, in which process the said constituents are spun from their melts simultaneously and side by side through common spinneret orifices and the spun filaments are then stretched at a temperature of 60 C. or less below the point at which the lower-melting constituent melts. An advantageous embodiment of the present process is to allow the filaments to crimp in the slack state and to heatset them in that state.

By subjecting the slack, crimped filaments to heatsetting, the half-value decrimping force can be substantially increased, where this is desired.

I have also invented an improvement in this process, which comprises spinning the two components, simultaneously and side by side, through three-armed spinneret openings. By this improvement, there are obtained composite filaments of trilobal cross-section.

The term three-armed is used to refer to spinneret openings made up from three slots starting from a common centre. The longitudinal sides of the slots may be parallel or non-parallel, they may be straight or curved and comprise distensions of any shape at the centre, at the ends or distributed anywhere over the longitudinal side in any desired manner. They may have differently shaped ends.

Filaments of trilobal cross-section have lately found extended use in various spheres, these spheres depending on the cross-sectional shape. While some shapes are used in woven and knitted fashion fabrics which are desired to have a glitter effect, others are suitable for use in upholstery and furnishing fabrics. In general it is claimed for trilobal filaments that they have in the textured state a considerable volume, a pleasant handle, better covering power, improved rigidity in the pile and that they seem to tend less to getting dirty.

For many of the aforementioned applications it has been found necessary to impart to the filaments, fibres or yarns a larger volume and with it an improved handle and improved heat-retention and covering power by a special crimping treatment, for example by a treatment in a stuffing box or in a whirl chamber, both combined with a heat-setting operation.

The spinning of composite filaments of different crosssectional shapes from polyamides and polyesters is known from United States Patent No. 3,117,906. However, filaments of these known shapes are not spontaneously crimping yarns and are filaments whose components separate, owing to the low stretching temperature, on being suitably after-treated, whereby very fine component filaments resembling natural silk are obtained.

The trilobal composite filaments according to the present invention may display different angles between the three anms. Furthermore, the cross-section may comprise convex, rectilinear or concave connecting lines between the three extremities. A clover leaf shape, on the other hand, is not indicated since such a shape is rather sensitive to a separation of the components in the individual arms. The ends of the arms are advantageously rounded ofi; in special cases they may be thickened. Furthermore, the arms may be of symmetrical or asymmetrical, identical or difierent shapes.

Starting materials suitable for use as the polyamide constituents are, for example, polyhex-amethylene adipamide (Nylon 66), polycaprolacetam (Nylon 6), polyhexamethylene sebacic amide (Nylon 610) and polyamideundecanoic acid (Nylon 11). In the composites of the invention which consists exclusively of polyamides, two polya-mides of different chemical composition, for example polyhexamethylene adipamide and polycaprolactam, are used and should lie side by side in the longitudinal direction of the filament.

As polyester constituents polyethylene terephthalate, copolyesters of ethylene terephthalate and ethylene isophthalate, or polyesters of terephthalic acid and di(hydroxy-alkyl) cyclohexane are, for example, suitable.

A prerequisite for the suitability of the said polymers for use in the present process is that the constitutents must not separate from each other. i

The spontaneously crimping composite filaments of the invention can be spun with the aid of devices of known type in which the two thermoplastic constituents are extruded through common spinneret orifices. When spinning according to the present invention it is possible to maintain, even over prolonged spinning periods, a controlled distribution of the two constituents over the crosssection of the composite filament, without mixing them from start to finish of the spinning operation.

The proportions of the two constituents in the composite filament can be varied by suitably setting the delivery rate of the titre pumps. The line of contact of the two constituents, as seen in the cross-section of the fibre, may be straight or bent and run along the axis of the fibre or be at a certain distance from it. In the limiting case the two constituents may take up symmetrical positions.

The filaments can be modified in a variety of ways by adding to one constituents or both constituents matting agents, coloured pigments, stabilisers, softening agents or the like.

The heat-stretching can be performed by any one of the suitable known method used singly or in combinations. The filament may be heated, for example, by means of heated feed rollers, stretching pins, heating surfaces or small heating tubes.

The heat-setting according to the invention of the filaments in the slack state can be performed immediately after the stretching or at any other subsequent stage of the manufacture. I

The crimp effect of the filaments manufactured by the present process is'three-dimensional, and sometimes even a double-spiral effect is observed. The crimp disappears when a high tensional force is applied to the filament but reappears spontaneously when this force is taken away. The crimp developed in the filaments is stable to storage even when the filaments are Wound under high tension. When the tensional force is taken off, the filaments recover their crimp.

The crimped filaments of the invention can be dyed, treated and finished like the known crimped fibres. In these operations the filaments should be treated in as slack a state as possible to avoid impairing the crimp.

The accompanying drawings illustrate a device for spinning trilobal composite filaments and illustrate also trilobal filaments both according to the invention and, for comparison, not according to the invention. In the these drawings:

FIGURE 1 is a cross-section through the device for producing filaments which are made up exclusively of composite components.

FIGURE 2 is a plan view of the same spinning device, seen from the outside of the spinneret.

FIGURE 3 is a spinneret opening having arms of unequal length.

FIGURE 4 is a cross-section through the trilobal composite components having arms of substantially identical length.

FIGURE 5 is a cross-section through a composite component not made according to this invention.

FIGURE 6 is a cross-section through a specular symmetrical trilobal composite component having arms of un- 4 equal length, produced with the aid of the spinncret shown in FIGURE 3.

In FIGURE 1, 1 represents the spinning device the interior of which is subdivided into two chambers 2 and 3 into which the molten polymers P and P are injected by means of one titre pump for each (not shown in the drawing); if desired filters may be provided downstream of the pumps. Through orifices 4 and 5 the two melts enter the chambers 6 and 7 and each contacts one side of the partition 8 which tapers off into an edge 9 in the vicinity of the spinneret orifices. Along this edge 9 the two polymer melts P and P meet and flow together, without mixing, through the spinneret orifices 10.

The edge 9, as used in the preferred variant of the process for the manufacture of composite filaments described in the following example, is disposed vertically above the centre line of the associated spinneret orifices 10. Alternatively, the same result can be achieved with an arrangement in which the edge 9 is not disposed vertically above said centre line, or in which no edge 9 at all is used, provided that in such a case the chambers 6 and 7 are very narrow.

It goes without saying that it is also possible to use devices having several parallel rectilinear edges 9 or having one or several circular edges 9 arranged in a coaxial fashion relatively to each other when no special demands are made on the uniformity of the cross-sectional shape and the crimping properties.

The slots starting from a common centre may be of identical or different length, depending on the desired properties of the filament to be formed. Furthermore, the angles includes between the individual arms may be identical or different, and also in this case a symmetrical or asymmetrical arrangment may be chosen.

The direction in which the cooling air is blown on to the filament cross-sections may be as desired so long as no stringent demands are made on the regularity of the filaments formed. It is however preferable to arrange one arm facing exactly in the direction of the air blast; when the arms are of unequal length, this is advantageously the longest or the shortest arm.

When a circular shape is chosen for the edges 9 this demand is somewhat more difficult to satisfy, but the identical effect can be achieved by locating the cooling air nozzles in the centre of the circle on which the spinneret openings are sited.

The edge 9 may be perpendicularly or set-off over the point from which the individual slots of the spinneret openings 10 start. Advantageously, it is arranged so that one arm of the filament cross-section is formed exclusively by one component and the other two arms are substantially formed by the second component of the composite filament.

The positions of the slots of the spinneret openings and of the associated edge 9 as well as its shape and the direction of the air blast are important factors in varying the cross-sectional shape of the filaments 10. It has been observed that maximum regularity of the cross-sectional shape, of levelness of shade and of uniform crimp can be achieved only when the following prerequisites are satisfied, as shown in FIGURE 3:

(1) The edge 9 should be rectilinear.

(2) The edge 9 should be located perpendicular above the point in which the slots of the spinneret openings coincide. g

(3) The slot 12 of length 1, from which only the component of lower viscosity issues, should be at right angles to the direction of the edge 9 and should be facing the direction of the air blast 11.

(4) The angle and the length of arms of the slots of the spinneret orifices should be specular symmetrical relatively to the perpendicular to the edge 9 (a=ot' 1'=1", i.e. the shorter arms are mirror images relatively to that perpendicular).

(5 When the spinneret openings are made up of arms of different lengths, the longest or the shortest arm should face the air blast.

As an example of the invention, there will now be described the production of trilobal composite filaments. In this example, the term reduced viscosity is computed from the equation:

Reduced viscosity: 1 ,7; rel./c

where in the case of polyamides a rel. is the relative viscosity of a solution having a concentration c=0.2 gram of polyamide per 100 cc. solution, measured at 20 C.

The solvent used is sulphuric acid of 94% strength; in

the case of polyesters 7 rel. is the relative viscosity of a solution having a concentration c=0.2 gram of polyester per 100 cc. solution, measured at 20 C. The solvent used is a 1:1 mixture of phenol and tetrachloroethane.

The spinning device shown diagrammatically in FIG- URES l and 2 of the accompanying drawings, having 6 spinneret openings, is used. Equal amounts of two molten polyesters are supplied to chambers 2 and 3. Chamber 2 is charged with a polyethylene terephthalate having a reduced viscosity of 0.600 and chamber 3 with a polyhexa-methylene adipamide which has been matted with 0.3% of titanium dioxide and has a reduced viscosity of 1.175. The spinneret openings are made up of 3 rectangular slots, all of 120 width and 925 length, which start from the same centre, are rounded off at the other end and include between them angles of 120; they are oriented with respect to edge 9 in a manner such that the arm through which the polyester of lower viscosity flows is at right angles to the direction of edge 9. The composite filaments are ejected from the spinnerets into a jet of cooling air; in FIGURE 2 the direction of this blast of cooling air is indicated by 11. The filaments are then reeled at a rate of 760 metres per minute (:filament A). This filament is completely smooth and has a substantially uniform trilobal cross-section as shown in FIGURE 4 of the drawing, one arm 13 of the filament cross-section consisting exclusively of polyethylene terephthalate and the other two arms 14- consisting substantially of polyhexamethylene adipamide. These two components are inseparable.

The unstretched composite filament A is streached to 2.51 times its initial length at a reeling rate of 188 metres per minute and at a temperature of about 185 C. (:filament B). When the tension has been taken off it, this filament B possesses the properties listed in the table.

Another sample of the unstretched composite filament A is stretched to 2.72 times its initial length with application of heat under identical conditions. When the tension is taken oil? it, this filament undergoes crimping (=filarnent C). The crirnped filament C is heat-set in the slack state for 15 minutes with water heated at 98 C. (=filament D).

The properties of filaments B, C and D are compared in the following table:

Titre Number of Filament Take-up Loops Denier (Tern) B 21 (2. 3) 66 5. 1 G 19 (2. 1) 68 7. 2 D 76 13. 5

The handle of the filament comprising trilobal composite components is harder and drier than is found with those having composite components of circular cross-section.

When a filament is spun from the same polyesters but through spinneret openings consisting of one long and two shorter rectangular slots including angles of between them, which coincide at one end, the spinneret being arranged so that the long slot faces the direction'of the air blast, the filament has the trilobal cross-sectional shape represented by FIGURE 6 of the drawing. The spontaneously crimping filament has a harsh, sandy handle.

When one of the two components is of very low viscosity and the air blast hits the filament in the direction of the edge 9, it is observed that the component of high viscosity issuing from the two shorter slots forms a circular filament from which protrudes the component of low viscosity ejected through the longer slot, as shown in FIGURE 5 of the drawing. Thus, when it is desired to form trilobal filaments a certain upper limit is set to the difference in viscosity of the two components. This can readily be ascertained by way of preliminary experiments.

The preceding example reveals the results with textile titres. As expected, the crimp-especially the number of loops in rather coarse titre filaments such as are used for carpets and furnishing materialsis not so high as with the fine titres, but this is not really a disadvantage because the resulting yarn volume is as such quite adequate for such purposes.

-I claim:

1. In a process for the production of a spontaneously crimping filament, which comprises simultaneously meltspinning two ditterent mutually adherent fibre-forming polymers through a spinning orifice, one of the polymers being a polyamide and the other a different polymer selected from the group consisting of polyamides and polyesters, so as to produce a composite filament having the two polymers arranged side by side along the length of the filament and adherent to each other, and thereafter stretching the filament at a temperature below but at most 60 C. below the melting point of the lower viscosity component and in which cooling air is blown on to the composite filament, the improvement which comprises spinning the component of lower viscosity through one slot of a three-armed substantially Y-shaped spinning orifice and the component of higher viscosity through the other two slots thereof and blowing the cooling air from the direction in which said one slot is directed so as to produce trilobal composite filaments.

2. The process of claim 1, in which the component of higher viscosity is spun through two slots of equal lengths and the component of lower viscosity is spun through a slot of length different from that of the other two slots.

3. The process of claim 2, in which the component of lower viscosity is spun through one slot which is directed in the direction from which cooling air is blown and which is longer than the other tow slots.

References Cited by the Examiner UNITED STATES PATENTS 3,017,686 1/1962 Breen et a1 264-177 X 3,117,906 1/1964 Tanner 188 3,192,295 6/1965 Settele 264-171 X FOREIGN PATENTS 112,550 2/1941 Australia.

904,869 8/ 1962 Great Britain.

936,729 9/ 1963 Great Britain.

957,534 5/1964 Great Britain.

ALEXANDER H. BRODMERKEL, Primary Examiner.

A. L. LEAVITT, I. H. WOO, Assistant Examiners. 

1. IN A PROCESS FOR THE PRODUCTION OF A SPONTANEOUSLY CRIMPING FILAMENT, WHICH COMPRISES SIMULTANEOUSLY MELTSPINNING TWO DIFFERENT MUTUALLY ADHERENT FIBRE-FORMING POLYMERS THROUGH A SPINNING ORIFICE, ONE OF THE POLYMERS BEING A POLYAMIDE AND THE OTHER A DIFFERENT POLYMER SELECTED FROM THE GROUP CONSISTING OF POLYAMIDES AND POLYESTERS, SO AS TO PRODUCE A COMPOSITE FILAMENT HAVING THE TWO POLYMERS ARRANGED SIDE BY SIDE ALONG THE LENGTH OF THE FILAMENT AND ADHERENT TO EACH OTHER, AND THEREAFTER STRETCHING THE FILAMENT AT A TEMPERATURE BELOW BUT AT MOST 60*C. BELOW THE MELTING POINT OF THE LOWER VISCOSITY COMPONENT AND IN WHICH COOLING AIR IS BLOWN ON TO THE COMPOSITE FILAMENT, THE IMPROVEMENT WHICH COMPRISES SPINNING THE COMPONENT OF LOWER VISCOSITY THROUGH ONE SLOT OF A 